1. Field of the Invention
The present invention relates generally to the field of drywall corner trim and more particularly to a boxable mesh adhesive drywall corner trim.
2. Description of the Prior Art
Drywall corner trim originally was metal corner bead. Several years ago, a new type of corner trim was invented that was a hinged plastic with paper covering. This type of trim is described in U.S. Pat. No. 6,148,573. U.S. Pat. No. 6,148,573 is hereby incorporated by reference. One problem with existing corner bead and trim products is that they were not boxable. By boxable, I mean the ability to put wet mud on both sides of the product without waiting for one side to dry. Historical trim products required the application of mastic or drywall mud compound to one side of a corner i.e. right or left; allowing that side to dry (generally throughout the construction project); sanding that side, and then applying wet mud to the second side, allowing it to dry, and finally sanding the second side.
U.S. Pat. No. 6,779,313 describes a boxable corner trim product that by the shape of the outer surface, allows wet mud to be applied (from a mud box) to both sides. This can greatly reduce the number of steps required to finish a construction job. This type of product is generally designed to be attached to the wall (drywall) using only wet mud behind the piece. However, on many occasions, it is also economical and desirable to attach the piece with adhesive. U.S. Pat. No. 6,779,313 is hereby incorporated by reference.
It is well known in the drywall industry that many corner trim materials are difficult to apply using mechanical methods of attachment such as nails or adhesive, and are very susceptible to damage after application and finishing. This can be caused by any impact or movement of the building. The damage usually takes the form of cracked edges at the flange edge of the material as the dried mud cracks during impact, or building structural movement. The result can be that the flange of the trim material delaminates and partially separates form the surface of the wall.
To try to mitigate damage, installers commonly use separate adhesives to better bond the corner trim material to the drywall corner and apply mesh material over the flange edge of the trim after installation. They then apply their first layer of mud over the mesh. A commonly used type of adhesive is a spray-on type. The mesh material is usually fiberglass that has some adhesive applied to one side (the side that faces the wall).
U.S. Pat. No. 5,442,886 teaches a corner piece with mesh and a layer of adhesive. One of the major problems with that system is that the piece is not boxable. Another problem is that the continuous layer of adhesive taught does not adhere uniformly to the drywall board. U.S. Pat. No. 5,442,886 is hereby incorporated by reference. U.S. Published Patent Application 2006/0283115 teaches a different corner trim with mesh. This system has similar problems. Publication 2006/0283115 is hereby incorporated by reference.
It would be advantageous to have a corner trim material that allows the installer to take a pre-cut piece of material and simply stick it to the wall using its supplied adhesive and mesh material. The adhesive can hold the corner trim material until an initial layer of mud or joint compound or other mastic can be applied for a permanent bond. The mastic material can migrate through the openings in the mesh and bond to the wall in a very strong, damage resistant fashion.